A blackout risk from electric cars has been discussed for years – and was actually considered unlikely. But are fan heaters supposed to endanger the power grid? FOCUS Online asked what that means for electric cars.
To get straight to the point: Neither fan heaters nor electric cars threaten a blackout in the true sense. Ultimately, this means a massive power outage that can last for weeks in entire regions or even countries, in which the high-voltage grids fail. But it could actually become a problem in the regional low-voltage distribution networks if, for example, millions of people suddenly turn on electric fan heaters next winter because of gas rationing.
Stadtwerke Wiesbaden, for example, warns of this: “Excessive use can overload our power grids and thus lead to uncontrollable power failures,” the municipal utility said in a statement. In the event of an overload, parts of the power grid would then be switched off to be on the safe side. And: Mobile devices such as fan heaters, radiators or radiant heaters could not be switched off by the municipal utility if there was a risk of overload. If mobile electric heaters were not switched off by the users in the event of a power failure, there was a risk of long outages.
Some people pricked their ears at this message: if a few million two-kilowatt fan heaters pose a problem – what challenges do the electric cars that have to fill their giant batteries pose for the power grid? So far, of the 15 million electric cars including hybrid vehicles planned by 2030, only one million are on the road. But the number of registrations of battery-powered vehicles is increasing rapidly and by 2035 at the latest, no new petrol and diesel cars will be allowed to be registered anywhere in the EU.
Battery cars usually charge at home in the garage. They draw considerably more power than a household appliance from special wall boxes with a charging capacity of 3.4, 7.4, 11 or a maximum of 22 kilowatts. The limiting factor is not just the home network, but also the car’s integrated charger; often the available charging capacity of the box cannot be used at all.
FOCUS Online asked the experts from the Association of Electrical, Electronic & Information Technologies e. V. (VDE) enquired. In fact, Germany faces major challenges if e-mobility is to ramp up smoothly:
It is clear that the current power grid is designed for low loads. A few decades ago, it was simply not in the planning that there would be masses of electric cars. So what if – as can be seen in the current energy crisis from the construction errors of the German energy transition, where, for example, power lines are missing – the network does not grow fast enough with the expansion of e-mobility? Especially since one has to assume that not all wall boxes are registered. Because the greater the problems in network expansion, the more likely the owner of an e-car has to reckon with the fact that the desired high-performance wall box will not be approved at all or only a “small” wall box.
After all: The unfavorable maximum case, that is, that everyone wants to charge their car with 22 kW in the garage, is actually ruled out. As early as 2019, Benedikt Kessler, head of network operations at energis-Netzgesellschaft mbH in Saarbrücken, said in an interview with FOCUS Online: “For a range of 100 kilometers, i.e. a classic commuter distance, you might need 15 to 20 kWh. If you charge at night, you don’t even need 11 kW of charging power. As a rule, even 3.7 kW would be enough for your battery to be fully charged again in the morning. Even the simplest Stromer can do that. “
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The reality in German garages will not be “big” wall boxes with a lot of charging power, but many small charging points with 11 kW or less. If you want to replace your petrol or diesel with an electric car, you still have to know that you may not be able to charge it everywhere and always, as you are used to when filling up your normal car. Because if the load expansion happens faster than the grid expansion, then “charging has to be done in a grid-friendly way”. In other words: Charging does not necessarily take place when the driver needs it, but when there is just enough electricity available.
The VDE explains what the prerequisite for grid-friendly charging is: a temporary shifting of loads using intelligent measuring systems (iMSys). The wallbox communicates with the network operator so that they have an overview of the current charging situation and can intervene in an emergency. “The alternative would be to allocate network connections for wall boxes according to the principle of first come, first serve or to switch off individual network strands temporarily in overload situations,” according to the network experts.
However, such a solution would not be in line with the ramp-up of e-mobility. And it would take German politics, which is completely focused on electric cars, ad absurdum. When a draft law on “peak smoothing” leaked out to the media in the last federal government under the then Economics Minister Peter Altmaier, the reactions were correspondingly clear: “What is called peak smoothing unfortunately means switching off for customers”, said the then President of the Automobile Association, Hildegard Müller “If that happens, it would be very bad for all EV owners and the companies that are now bringing EVs to market.” “
However, the disadvantage of peak smoothing could be offset by another advantage: if you charge flexibly, you also get flexible electricity tariffs. The basis for this is the newly created Section 14a EnWG (Electricity and Gas Supply Act (Energy Industry Act)), which states: “Operators of electricity distribution networks offer those suppliers and end consumers in the low-voltage sector with whom they have concluded network usage contracts a reduced to calculate the network fee if, in return, the network-friendly control of controllable consumption devices that have a separate metering point is agreed with them. Electric vehicles are also considered to be controllable consumption devices within the meaning of sentence 1. “
This means that anyone who allows their wallbox to be controlled remotely by the electricity provider should then pay less for charging. This could be interesting for second cars in particular, which are usually driven at fixed times, for example on the way to work – and which then hang on the charging cable for the rest of the day until they are needed again the next morning.
All electric car and plug-in hybrid models at a glance
The Network Operators Forum of the VDE has developed a traffic light system as a proposal for intelligent charging control, with which every owner of an e-car could recognize before possible shutdowns when it is best to charge their vehicle and when not:
The integration of millions of electric vehicles into the power grid does not happen overnight and can therefore not be compared with the “heater problem” that is feared in winter 2021/22. However, e-mobility will make it necessary to expand the grids and also to use intelligent charging control. Many details are still being planned and discussed, the first legal framework will be available shortly. To ensure that e-cars do not overload the regional distribution networks, every owner of such a vehicle must always expect that their charging station will be switched off remotely.
On the other hand, a power grid that is no longer demand-oriented but supply-oriented also offers the possibility of “rewarding” flexible users with temporarily lower electricity costs. In particular, those who only need their e-car as a second car in addition to the petrol or diesel engine that can be used at any time, or who can do without a car altogether in an emergency, could even drive particularly cheaply in the future.
